The present invention relates generally to a fastener machine, and more particularly, to a rivet guide head that guides a rivet during a rivet machine drive stroke.
Rivet machines generally include a punch that is configured to engage and drive a rivet through workpieces to join the workpieces together. In general, the punch directs the rivet through a rivet guide head that guides the rivet in a desired orientation toward a selected area on the workpieces. With reference to FIGS. 2-9 of the Figures, one guide head constructed in accordance to the prior art is shown and generally identified at reference numeral 10. The guide head 10 is generally mounted to a punch guide 12. The guide head 10 generally includes a first pair of opposing plunger assemblies 14 and a second pair of opposing plunger assemblies 16. The first pair of opposing plunger assemblies 14 includes plungers 20 that are biased inwardly by biasing members 22. Similarly, the second pair of plunger assemblies 16 includes a second pair of plungers 24 that are biased inwardly by a second pair of biasing members 26.
A first pair of set screws 30 secures the first pair of plunger assemblies 14 to the guide head 10. A second pair of set screws 32 secures the second pair of plunger assemblies 16 to the guide head 10. During operation, the respective plungers 20 and 24 act on an outer surface 36 of a rivet 40. In this regard, the plungers 20 and 24 translate in a direction perpendicular to a guide bore axis to follow an outer profile of the surface 36 of the rivet 40 through the drive stroke.
As shown in FIG. 7, the first pair of plungers 20 are biased inwardly to contact an innermost diameter of the rivet 40 during translation of the rivet 40 through the guide head 10. The components of the guide head 10 according to prior art can pose a number of problems. For example, the plungers 20 and 24, the biasing members 22 and 26, as well as the set screws 30 and 32 are all relatively small pieces that can be difficult to assemble and tend to inadvertently be lost. The spring tension of the biasing members 22 and 26 is generally set by the respective set screws 30 and 32. Assembly of the set screws 30 and 32 can be difficult and generally awkward. In many examples, it is required to apply a flowable adhesive to an interface between the set screws 30, 32 and the guide head 10. In some examples during use, the rivet 40 can be caught or trapped between the first set of plungers 20 and the second set of plungers 24 (see FIG. 8). In other examples, the rivet 40 may become caught elsewhere such as between the second pair of plungers 24 prior to being driven into a workpiece.
In accordance with the present invention, a rivet guide head that guides a rivet during a rivet machine drive stroke is provided. The rivet guide head includes a rivet guide body having a rivet guide surface defined along a rivet guide bore having a guide bore axis. A first elongated guide pin is disposed in the rivet guide head that extends along a first guide pin axis and has an outer engagement surface. The guide bore axis is substantially parallel to the first guide pin axis. The rivet guide head is configured to guide the rivet along the outer engagement surface of the first elongated guide pin during the drive stroke. According to further aspects, the first elongated pin deflects laterally outwardly during the drive stroke. A first biasing member is disposed in the rivet guide head and is configured to bias the elongated guide pin in a direction toward the guide bore axis.
According to still other aspects, the first biasing member comprises an elongated elastomeric member that extends along a first member axis that is parallel and laterally offset from the guide bore axis. The rivet guide head is configured to slidably and concurrently engage the rivet at the rivet guide surface with the engagement surface of the first elongated member during the drive stroke. According to another aspect of the present invention, the first elongated pin deflects to a guide position upon initial engagement with the rivet and substantially remains at the guide position subsequent to the initial engagement through the drive stroke until the rivet is urged to a location adjacent a terminal end of the first elongated pin. In other features, a second elongated guide pin and a second biasing member are both disposed in the rivet guide head and cooperate with the first elongated guide pin and first biasing member to guide the rivet through the rivet guide head through the drive stroke.
Further advantages and areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention.
Corresponding reference numerals indicate corresponding parts throughout the several views of the drawings.